Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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FXUS66 KSEW 242142

Area Forecast Discussion
National Weather Service Seattle WA
242 PM PDT Tue May 24 2022

.SYNOPSIS...A weak weather system will bring a slight chance of
rain through tonight. A cold front will move through the area
late Thursday follow by another system Saturday into Sunday. This
is expected to result in widespread precipitation for at least the
first half of the Memorial Day weekend.


.SHORT TERM /TONIGHT THROUGH FRIDAY/...A weak weather system
moving into BC will brush the region this afternoon through early
Wednesday bringing a slight chance of precipitation. Significant
impacts beyond wet roads are not expected. Brief ridging will
return late Wednesday into early Thursday before a shortwave sends
more energy across the region late Thursday into Friday. There
may be enough instability to generate some isolated thunder
Thursday afternoon or evening. Precipitation will taper off
through the day Friday.

Temperatures will likely peak Thursday ahead of the shortwave in
the mid 60s to around 70 in the lowlands.

.LONG TERM /SATURDAY THROUGH TUESDAY/...Stop me if you`ve heard
this before...another wave (or weak closed low) will pass to our
south Saturday as a longwave trough amplifies over the western US.
This will result in widespread precipitation chances Saturday into
Sunday. By Sunday night the bulk of the energy will be south of
the area and shower activity is likely to gradually diminish as
western WA lies in the northerly flow between the western trough
and an offshore ridge. This will result in cooler temperatures
(highs Sunday may struggle to reach 60). While confidence begins
to wain early next week, it does appear that a period of at least
weak ridging may allow us to warm back up toward normal by


.AVIATION...A weak upper level ridge over the area today will
flatten out tonight. SW/S winds 5-10 kts expected for most
terminals. Ceilings of 4,000-5,000 feet expected at most terminals
to persist through the evening hours, into Wednesday morning. The
exception being like KHQM, KOLM, KPWT where patches of MVFR may
be observed during the early morning hours of 08z-10z.

KSEA...Ceilings 4,000-5,000 feet this evening and into the
overnight hours. SW winds turning more southerly 5-10 knots into
Wednesday morning. Dry conditions are expected tonight into
Wednesday morning. There may be lower ceilings in the vicinity of
the terminal tomorrow morning, but the confidence of low clouds
reaching the terminal is low.


.MARINE...High pressure will persist over the waters tonight with
onshore flow weakening this afternoon. Benign conditions will
reign for the remainder of the period, with weak onshore flow
Wednesday morning. A weak front will reach the area Wednesday with
a stronger system arriving Friday. As of now, there are no SCA
headlines are expected to be issued with this system. Another
system will pass us to the south Saturday.



.HYDROLOGY...The daily hydrology discussion has ended until the
start of the next rainy season; it will only be updated as needed
until then.



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